Third-generation cellular radio networks based on WCDMA are poised to come into service within a couple of years. Recently, receiver IC's in both BiCMOS and SiGe BiCMOS technologies have been reported for the new standard.
The goal ofthis overall project is to demonstrate the feasibility ofa highly integrated UMTS transceiver in deep submicron CMOS technology using a direct-conversion architecture in the receive as well as the transmit path. In the transmit path, to minimize the carrier leakage, a double-balanced, current-commutating mixer is used for the upconversion. The implemented mixer topology guarantees a wide and accurate gain control range, high linearity, low noise while at the same time minimizing the voltage headroom requirements.
The complete transmit modulator including a baseband filter, an I/Q divider and an I/Q modulator has been implemented and fully characterized in a 0.25 um CMOS process and shows excellent results.